Dear Nima, if you mean molecular phylogeny, there is obviously DNA sequence of the animal. Did you try BLAST?

https://blast.ncbi.nlm.nih.gov/Blast.cgi

Please also see the publication:

Article DNA-based species delimitation in algae

In its major part, the content is applicable to animals.

Best wishes,

Ivan

Dear Mr. Pchelin

thanks for your consideration,

The problem is that the mentioned site doesn't have the gene sequence we want.

We are looking for a way to find the desired gene sequence by using species that are both close to the target animal and have the desired gene sequence.